There are many situations in which practical difficulties arise because a shielded cable is exposed to relatively large electromagnetic interference fields which induce interference voltages in the shield that can be carried along the cable to a point where they could damage or substantially impair equipment interconnected with the cable. On board ship, for example, there are many situations where equipment located below deck is connected to other equipment located above the deck with interconnections being provided via shielded cables which would normally be exposed to substantial interference electromagnetic energy, such as generated by the ship's radar. It is, therefore, highly desirable to ground or terminate the cable shield to the deck or adjacent superstructure before the cable passes through the deck to internally located utilization equipment. This problem is especially severe in naval craft where electromagnetic fields produced by radar gives rise to an interference field of relatively high level.
In the event of a nuclear explosion, an electrical pulse (EMP) of such magnitude is generated as to destroy communications and wipe out data bases in computers, for example, over a geographical area substantially exceeding the blast area of damage. Such a problem not only would have severe consequences for the public generally, but also would be devastating on military electronics. Shielding of sensitive electronic circuits, components, and cables by enclosing them within a conductive member that would conduct such EMP energy to the ground can be effective, if properly handled. However, any gap that may exist in the conductive path to ground could result in destruction of the protective circuitry and, therefore, to be fully effective such grounding protection must exist not only on the cables themselves but also at any connector for the cables.
The most common approach to solving or reducing this problem in the past has been simply interconnecting a single element conductor (so-called "pig tail") between the cable shield and a grounding point such as the deck. A pig tail interconnection is, of course, only to a single limited point on the shield and would not be sufficient to removed induced signals of a relatively high level, at least to the extent necessary to avoid damaging interference to interconnected equipment. Moreover, typical one point connection by a pig tail leaves exposed parts of the shield which can result in deterioration of the shield and pig tail due to adverse environmental factors.
A further approach is that disclosed in copending U.S. patent application Ser. No. 642,170, Cable Shield Grounding Apparatus by M. K. Van Brunt et al. and assigned to the same assignee as the present application, in which a spring member has a plurality of contact fingers that are pressed against the cable shield by a containing cylindrical part. A cap is threaded onto the cylindrical part, and the latter is welded to the grounding plate (e.g. ship deck).